Disk rolls have been used, for example, to convey a sheet glass flown down from a melting furnace or to convey a heated metal plate such as a stainless steel plate in an annealing furnace (for example, see Patent Document 1). As shown in FIG. 1, the disk roll 10 is one that a plurality of ring-shaped disks 12 containing inorganic fibers or an inorganic filler are fitted on a metal-made shaft 11 as a rotating shaft by insertion to form a roll laminate and the whole roll laminate is pressurized through flanges 13 provided at both ends and fixed by nuts 15 in a state of applying slight compression to the disks 12. Outer peripheral surfaces of the disks 12 function as a conveying surface.
In the disk roll, the shaft 11 on which the disks 12 are fitted by insertion is made of a metal. Therefore, when the disk roll is exposed to high temperature, the shaft 11 thermally expands and elongates along a shaft direction. In this case, there is a concern that because the disk 12 is made of ceramics having a coefficient of thermal expansion lower than that of a metal, the disk 12 cannot follow the elongation of the shaft 11, and thereby the disks 12 may separate with each other, resulting a disk separation (the phenomenon that gap is generated between the disks). Further, there is concern that cracks are generated on the roll surface (conveying surface) caused by thermal stress due to temperature difference (thermal expansion difference) between outside (peripheral surface) and inside (inner portion) of the disk. To avoid those disadvantages, scale-like materials such as mica have been blended to the disk in many cases (for example, see Patent Documents 1 and 2). That is, mica has extremely thin layer structure, and also has a tendency that when heated, it releases crystallization water to cause crystal modification, and expands in a layer direction. It is expected that the follow-up properties to thermal expansion of the shaft material 11 of the disk 12 can be improved by the expansion of mica in a layer direction.